1. Field of the Invention
The present invention relates to novel detachable tip assemblies for cue sticks. It also relates to cue sticks having such novel detachable tip assemblies.
2. Description of the Related Art
Players of billiards and pool and similar billiard table games use cue sticks for striking balls during the course of play. A cue stick has a grip end and a striking end. The striking end is typically fitted with a shaft ferrule to which an impact-protection tip pad is attached by an adhesive. A shaft ferrule is often referred to in the art simply as a “ferrule,” but the term “shaft ferrule” is used herein and in the appended claims for greater clarity when reference is being made to the conventional cue stick ferrule. The shaft ferrule absorbs some of the shock during ball striking thereby protecting the cue stick shaft from impact damage, e.g., splitting. Shaft ferrules are typically made of high-impact materials that are resistant to cracking, chipping, and breaking, e.g., brass, ivory, carbon fiber, plastics such as melamine resin, aegis, or phenolic resin.
The tip pad is often referred to in the art simply as the “tip”, but the term “tip pad” is used herein and in the appended claims for greater clarity. The tip pad provides the interface during striking between the ball and the rest of the cue stick. Tip pads typically have the shape of a disc or a short cylinder. One face of the cylinder is typically flat and seats upon the outer face of the shaft ferrule to which it is held in place by a bonding layer of an adhesive. The other cylinder face is the striking face of the tip pad and usually has a convex shape with a desired degree of curvature.
Tip pads come in different hardnesses and with different diameters and striking face curvatures. Hard tip pads are favored for high-impact shots, e.g., breaking shots, and may be made of phenolic resin or leather. Softer tips pads are favored for placement shots, especially when the player desires to put spin on the ball being struck. Softer tip pads are typically made of multiple layers of compressed-together leather, although one-piece leather tip pads are sometimes used. The level of hardness that a multiple-layer leather tip pad has depends on the amount compression pressure that was used in making it, the greater the compression, the greater the hardness.
Tip pad diameters vary within ranges which are related to the type of game for which the cue stick is intended for use and an individual player's preference. Cue sticks which are intended for use in playing pool usually have tip pad diameters of between about 1 to about 14 millimeters, with 13 millimeter being the most common. Cues sticks which are intended for use in playing snookers generally have tip pads of smaller diameters, the most common being 9.5 millimeters.
The radius of curvature that a tip pad has on its striking face is preferably chosen to correspond to the amount of spin that the player desires to put on the struck ball. Lesser degrees of curvature provide for less spin, especially accidental spin, thus yielding straighter shots, e.g., for breaking. Higher degrees of curvature make it easier to impart spin to the struck ball. The degree of curvature varies inversely with the radius of the curvature. The radii of curvature typically used for striking faces are those corresponding to three United States coins, i.e., the dime (8.95 millimeters), the nickel (10.6 millimeters), and the quarter (12.15 millimeters).
The striking face of a tip face is usually made with a controlled level of surface roughness. Greater roughness provides for better ball gripping during impact thereby making it easier to impart spin to the struck ball. Smoother tip pads make it less likely that spin will be accidentally imparted to the struck ball.
Repeated ball impact causes wear damage to the tip pad. The shape of the striking face will change, often flattening and becoming distorted. The tip pad may also mushroom out over the side of the shaft ferrule. The striking surface also becomes smoother making it more difficult to control the amount of spin given to the struck ball. High impact shots, such as breaking shots, are particularly damaging. As the tip pad damage accumulates, the player's shooting accuracy is likely to decrease. Cue chalk is typically applied to the striking face of the tip pad before every shot as a means of both decreasing the rate of damage accumulation and compensating for the damage already present. Shaping tools are sometimes used to partially restore the shape and surface roughness of the tip pad by cutting or abrading the tip pad. However, shaping tools are of limited effectiveness and can only be used a finite number of times before too little tip pad remains to be worked upon.
Compounding the problem of tip pad wear damage are rules of play that sometime prevent a player from changing cue sticks during the play of a game.
Conventionally, a damaged tip pad can be removed by breaking or dissolving the adhesive layer that holds the tip pad to the shaft ferrule or by cutting away the tip pad. Once removed, a new tip pad can be glued into place. However, this method of repair is time-consuming and is often inconvenient to conduct, especially during the play of a game.
Over the years, there have been numerous attempts to address the problem of tip pad damage through different schemes for improving the replaceability of the tip pads. Examples of such schemes are disclosed in U.S. Pat. Nos. 7,097,570 B2, 6,719,638 B2, 6,183,371 B1, 5,462,490, 3,580,576, 3,226,119, 2,544,970, 1,614,414, 1,544,696, 1,532,985, 1,476,622, 1,429,752, 1,340,395, 1,257,249, 1,141,587, 1,077,664, 1,013,671, 985,067, 934,162, and 52,128, as well as in U.S. Patent Application Publication Nos. US 2007/0219009 A1, and US 2007/0066411 A1. However, all of these schemes suffer from one or more of the following disadvantages: undue complexity, added heaviness, and proneness to unintended loosening of the component holding the tip pad.